Telephony.



E. R. CORWIN. TELEPHONY. Arrmoulol mlm $11124, 1911.

1,105,345. Patented July 2s, 1914 UNTTED sTATEs PATENT OFFICE.

ELMER R. COR/WIN, OF CHICAGO, ILLINOIS, ASSIGNOR, BY MESNE ASSIGNMENTS, T0 FRANK B. COOK COMPANY, 0F CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

TELEPHONY.

To all whom t may once/11n:

Be it known that I, ELMER REEDy CoRwiN, citizen of the United States, lresiding at Chicago, in the county of Cook and State of Illinois, have invented a certain new and useful Improvement in Telephony, of which the following is a full, clear, concise, and exact description, reference being had to the accompanying drawings, forming a part of this specification.

My inventionlrelates to telephony and has for one of its objects the provision of a telephone system including two or more telephone lines; a third telephone line; and means whereby either of the first telephone lines may become connected with the third telephone line and establisha busy test condition in connection with the third telephone line. and whereby the telephone of the station initially becoming connected with the third telephone line maybe disassociated from said third lines without removing said busy test condition and may be again restored to connection with Said third line so that during the interval of disconnection of such telephone line the third telephone line may not be appropriated by another station.

My invention has for another of its objects the provision of apparatus brought into cooperative relation with the third telephone line by the station initially becoming connected therewith for lbcking out telephonie apparatus of other stations seeking the third telephone line, and whereby thel telephone at the station that-has'become initially connected with the third telephone line may\be,dis

associated from such line without rendering the lock out condition ineffective.

extending between the stations of the interior telephone system and an exchange, the

aforesaid third telephone line then constituting the trunk line.

Another feature of iny'invention resides in the provision of means whereby an inter-l communicating station., inv seeking connection with the station associated with a trunk line., taken for use. will have ,itst telephone y' locked ont and will .also have a busy test manifestation tc indicate that the wanted trunk line is busy.

Specification of Letters Patent.

Application led Apn'l 24, 1911.

Patented July 28, 1914.

Serial No. 622,943.

My invention has for another of its objects the provision of a plurality of trunk lines intervening between a telephone exchange and the telephone stations of a plu'- rality of Itelephone lines: signal apparatus at the telephone exchange adapted for association with the trunk lines and controlled by the apparatus at said telephone stations; and means interchangeably associated with said trunk lines operating in conjunction with said telephone stations for governing said signal apparatus. In the preferred embodiment of my iiivention the means for rendering the lock out and busy test condition, to prevent an appropriated trunk `line from again being appropriated while the trunk line isvin use, are interchangeably associated with the trunk lines.

I will explain my invention more fully by reference to the accompanying drawing showing the preferred embodiment thereof and which diagrammatically illustrates two stations of an intercommunicating system and two trunk lines extending to .said stations from an exchange.

Intercommunicating station No. 1 and intercommunicating station No. 2 are associated with circuits and apparatus shown in the'drawing below the same, whereby each of the stations may be selected by--thefparty `at ythe otherwhen free for selection, and may be signaled when thus selected, 'and whereby either station seeking the other when the other is busy will secure a busy test manifestation and will have its telephone locked out of circuit relation with the wanted station, all as will be readily understood by those familiar wit-h the practical art. I will therefore not go into detail in describing the inter-relation of station No. l and station No. 2. A trunk line 3 and a trunk line 4 are illustrated as extending from a telephone exchange to each of the stations of the intercommunicating.system, room, however, permitting only of the diagrammatic illustration of some telephone exchange equipment shown at the left of the `trunk line 4., 'which trunk line is diagrammaticallyindicated as terminating in the line spring of spring'jack 5 at the exchange, at which exchange one spring jack 6 belonging to one of many lines is also illustrated and'which may be connected with the jack 5 by means of any suitable cord connecting,

apparatus 7 'that is adapted to connect the trunk line with such a jack as the jack 6. A line indicator 8 'individual to. the trunk line 4 (there being some sort of line indicator individual, to v each trunk line) is bridged between the sides of the trunk line by a bridge connection that includes a battery 9, circuit v being closed through this battery at an intercommunicating station appropriating the line. At each intercommunicating station there is a signal receiver 10 individual to one of the trunk lines whereby each intercommunicating station may be signaled from the exchange.

There is provided at each of the intercommunicating stations a plurality of selecting keys 11, one individual to each trunk line and each adapted for coperation with a pin 12 mounted upon a connecting bar 13, whereby each key upon being fully depressed will release its companion so that one key will always occupy a position to which it is actuated, the lower keys 11 being shown in normal positions. The control that each station has over the trunk line is similar to that possessed by the other yand I will therefore describe in detail the association of but one of the intercommunicating stations with the trunk lines with the understanding that such description would apply to .each of the other intercommunicating stations, and at this point it should be stated that while my invention has been embodied in connection with an intercommunicating system, I do not limit myself to the use ot' my invention in connection with intercommunicating stations. Let it be assumed that station No. 1 desires connection with trunk line 4 and thereafter desires to hold that trunk line so as to esta lish connection with trunk lline 3 or for some other reason. The

party at station No. 1, in order to accom-` plish these objects, will fully`depress the selecting key 11 individual to trunk line 4 after having removed his telephone from its switch hook. As a consequence of this operation circuit through the battery 9 and the line indicator 8 is closed by way of the sides of the trunk line and a brid e across the sides of the trunk line that 1s establishedy switch contacts 111 of the selecting key 11 to* the other side of the trunk line.,

The manner in which the relay 15 is e11- ergized at this stage of the operation is known to those skilled in the practical art and may be described as resulting from a "actuated selecting key or switch 11 individual to the trunk line 4. A locking circuit is then established for the relay 15 which may be traced from the upper terminal of the battery 16 through the upper contacts of the switch hook at station No. 1, the left hand armature switch of relay 17, the winding of relay 15, the left hand armature switch of relay 1-5 and its Vlowermost contact to the lower pole of the battery 16. As a result, the line signal 8 at the exchange is operated and is responded to by the operator at the exchange in the usual way and the operator extends the trunk line into connection with a line wanted by station N o. 1 by means of usual or link connecting apparatus at the exchange. lThe'cord circuit 7 is provided with supervisory signaling apparatus individual to the trunk yend thereof as indicated diagrammatically at 19, and supervisory signa ing apparatusA individual to the other end th reef diagrammatically indicated at 20. The battery, indicated at 21, is connected across the* cord circuit from which current iiows through the supervise y signaling device, the circuit throughhe supervisory signaling device 19 100 including the right hand half of the cord circuit, the two sides of the trunk line 4, and the Ibridge circuit at station No. 1 which has been hitherto traced. If the party at station No. 1 should desire to disconnect his tele- 105 phone from and at the same time hold the trunk line 4 after having secured connection with another party by way of the exchange or after the exchange subscriber has secured connection with station No. 1 by way of the 110 trunk' line, then the party at station N o. 1 will depress a holding key 22 to bring the normally disassociated relay 23 into association vwith the trunk line that is to be held, each key 22 at each station being adapted 115 when operated to bring about the association of the relay 23 with the trunk line to which such key is individual and to remove such relay from association with a trunk line with which it was previously associated owing to 120 the mechanical interrelation between the keys 22 that enables each key to restore each other key 22 to normal position. A releasing key 24 serves to release any key 22 at its station so that the relay 23 will have no op- 125 erative association. Under the assumption that the trunk line 4 is to be retained by the part-y at station No. 1, the key 22 individual to the trunk line is placed in the position indicated, whereby a partial circuit is es- 130 completed when the button is actuated,

each switch 22 being associated with a vbutton or switch 25, there being one such switch 25 for each trunk line.

The circuit for the relay 23 that is established by the cooperation of the switches 22 and 25 may be traced from the upper pole of the battery 21', through the tip of the plug inserted in jack 5, .th'e'upper side ot the trunk line 4, the contacts ofthenow actuated key 25, the contacts 26 of key 22, the winding of relay 23, the contacts 27 of key 22, the lower side of the trunk, line 4, the sleeve of the plug engaging jack 5, to the lower pole of thesbattery 21. The relay 23 thereupon establishes a locking circuit through itself and it will be sufficient to trace a bridge connection between the sides of the trunk line through the winding of the relay 23, and which bridge connection is traced from the upper side of the trunk line 4, through the contacts 28, the right hand armature switch of relay 23 and its then engaged contact, the winding of relay 23, the contacts 27, to the lower side of the trunk line. There isthus established a bridge lacross the trunk line in place of the bridge hitherto traced through the telephone equipment at station No. 1 so that the breaking of the bridge that included the telephone at station No. 1, and which breaking occurred by the depression ot' the key 25, is not followed by a signal at 19 at the exchange. It is understood that when the key 25 is depressed the telephone equipment at station No. 1 is disconnected from the trunk line 4 because ot the consequent release of the button lll, which release is followed by the breaking of the bridge ineluding the telephone at station No. 1 and which breaking occur at the key 11. The party at station No. is now at liberty to hold conversation with another intercominunicating party, or any other party without the danger of having his conversation transmitted over the trunk line.

When the party at station No.` 1 desires to resume connection with the party connected with trunk line 4 he presses the button 11 at his station which is individual to the trunk line 4 so as to reestablish the telephone bridge between the sides ofthe trunk line at his station and which telephone bridge was previously traced. This telephone bridge is of low resistance compared with the resistance of the relay 23 so that the relay" 23 is denergized to break the bridge that said relay previously held across the trunk line whereby thc apparatus at station No. 1 is again placed in control of `the' signal 19 to enable said signal to respond when the telephone at station No. l is restored upon its switch hook thereby to break the only bridge thenexisting kat sta- Jtion No. 1 to open the circuit including the signal 19 and thereby cause it to operate.

I will now more particularly describe the means,'which constitutes an important feature of my invention, whereby the relay 23 at each intercommunicating station may be used for the purpose which has been described in connection with any ot the truuk lines so that it will not be necessary to provide a relay 23 individual to each trunk line at each station. When the relay 23 is unassociated with any trunk line its terminals are free of connection. Each of the terminalsoi the relay 23 is multiplied, the upper or right hand terminal being multiplied to each of the upper contacts'of the contacts 26 while the lowerv or lett hand terminal ot said. relay is multiplied to each of the upper contacts of the contacts 27. Owing to some previous operation of the key 24, the keys 22 are normal so that these multiplied terminals of the relay 23 are disconnected. It has been described how a depression of the keys 22 and 25 of trunk line 4 will associate the-relay 23 with the trunk line 4 and it will be obvious that asimilar depression of the key 22 associated with the trunk line v3 will bring about a similar association of the relay 23 4with the trunk line 3 when the key individual to the trunk line 3 is operated after the associate key 22 is operated, the key 25 individual t0 the trunk line 3 having an association with said trunk line similar to the association of the otherkey l25 individual to the trunk line 4. The circuit which was previously traced as a result of the operation of the keys 22 and 25 individual to the trunk line 4 finds its counterpart in the circuit which results from the depression of the keys l22 and 25 individual 105 to trunk line 3.

I will now describe the circuits and apparatus by which an appropriated trunk line is rendered busy so that. another intercommunicating party seeking connection there- 110 with will know of its busy condition and how the telephone apparatus of an interl communicating party seeking connection with an appropriated trunk line is prevented from having telephonie connection 115 with such trunk line.

Let it be assumed that the party at station No. 2 desires connection with the trunk line 4 at any time after it has been appropriated and whether or not itis held by the appa- 120 ratus at the intercommunicating station con. nected therewith. `The party at the seeking station, station No. 2, first-removes his telephone from its switch hook whereby a circuit is established which may be traced'from 125 the upper pole of the battery 16 through, the

`uppermost contacts of the switch hook at lav and its normal contact which is a follow I-'IU' up contact, the contacts 29 and 30, the contacts 31 of the now fully depressed key 11 individual to the trunk llne 4 at station No. 2, the conductor 4, the contacts 31 of the key l1 at station No. 1 (it now being assumed that telephone station No; 1 is in telephonie connection with the trunk line 4) the normally positioned contacts 32 at station No. 1, the left hand armature switch of relay l5 and the middle one of its contacts, to the lower side of the battery 16. At this point it will be explained that an alternate circuit connection is established from the contacts 31 at station ilo. 2 in the event of the key 11 occupying its normal position and of the relay 23 retaining a ,holding bridge across the trunk line 4 in order that the telephone apparatus at station No. 1 may be disconnected from said trunk line without allowing said trunk line to be appropriated by a seeking station. This alternate circuit is similar` to. the circuit similarly tra-ced up to thecontacts 31 at station N o. 2, the circuit then continuing from these contacts 31 to the then engaged contacts 33, the two uppermost contacts of the then actuated key 22, the left-hand armature switch of relay 23 to the lower pole of the battery 16.v With either circuit the right hand armature switch of the relay 17 at station No. 2 makes connection with its alternate contact before it breaks connection with Yits normal contact, whereby a looking circuit is established for the relay 17 at station No. 2 which may be traced from the upper terminal of the battery 16 through the uppermost contacts of the switch hook at station N o. 2, the winding of the relay 17 its right armature and its alternate contact to the lower pole of said battery.

The magnet 17 after having been energized lestablishes a busy test .circuit which may be traced' from the upper pole of the.

battery' through, the circuit interrupting apparatus 34, the middle armature switch of relay 17, its thenengaged contact, the switch hook at station N o. 2, the receiver and transmitter at station No. 2, the right hand armature switch of relay 15 at station No. 2 and its normal contact, to the lower pole of the battery 16 by way of the upper side of the intercommunicating telephone line leading to station No. 2.

As the relay 15 at station No. 2 has to be energized in order to include the telephone at said station in bridge of the line leading to station No. 2, and as the circuit of this relay depends upon the engagement of the left hand armature switch of relay 17 with its contact, the telephone outfit at station No. 2 is excluded from circuit owing to the vfact that the relay 17 at station No. 2 was energized as a consequence of the circuit connections resulting from the operation of the' key 11 at station No. 2 `individual to line 4 and which circuit connections were hitherto -traced. Thus the telephone at station No.

I believe it to be broadly new with me to l establish the test and lock out features in connection with trunk lines and the apparatus for holding the trunk lines busy while temporarily disconnected from a telephone station previously connected therewith, whether or not the means for rendering' the trunk line busy and for locking out the telephones of other stations are interchangeably related with the trunk lines.

While I have herein shown and particularly described one type of equipment carrying out my invention, I do not wish to be limited thereto as changes may readily be made without departing from the spirit of my invention, but

Having thus described my invention, I claim as new and desire to secure by Letters Patent the following:

. 1. A telephone system including two-telephone lines extending from telephone stations and each extending from its own station to .the station of the other line, there being means governed at the telephon'e stations whereby telephonic connection may be effected between the stations; a third telephoneoline; means whereby either of said telepohone stations may -become connected with the third telephone line, vand establish a busy test condition in connection with the third telephone line; and means whereby the telephone of the station initially becoming connected with the third telephone line may be dissociated from said third line without removing said busy test condition and may be again restored to connection with said third line so that during the interval of disconnection of such telephone line the third telephone line may not be appropriated by another station.

2. A telephone system including two telephonev linesextending from telephone stations and each extending from its own station to the station of the other line, there being means governed at the telephone stations whereby telephonic connection may be effected between the Stations; a third telephone line; means whereby either of said telephone stations may become connected with the third telephone line; apparatus brought into cooperative relation with the thirdy telephone line by the station initially becoming connected therewith for locking out telephonie apparatus of other stations seeking the third telephone line; and means whereby the telephone at the station that has initiallyv become connected with the y Lrhsgsh third telephone line may be dissociated fron such line without rendering iifeii'ective the lock out condition, and whereby 'siibh telephone may be restored to its connection with the'third telephone line so that during the interval of disconnection of such telephone line the third telephone line 'may not be appropriated byanother telephone station..

c'onn'e'cted with the trunk line may be dis` sociated from said trunk line wi o'iit r- `moviiig said busy test condition and may be again restored to connection with said trunk line so that during the' interval of disconnection of such telephone line the trhl line may not be appropriated by another station.

4. A telephone system including two telephone lines extending from telephone stations and each extending from its ownstation to the station of the other line, thr'e being means governed at the' telephone stations whereby telephonie connection may be effected between the stations; a telephone exchange; a trunk line intervening between the stations of the aforesaid lines and said exchange; means whereby either of said telephone stations may become' connected with the trunk line; apparatus brought into cooperative relation with the trunk line by the station initially becoming connected therewith for locking out telephone apparatus of other stations seeking the trunk line; and means whereby the telephone at the 'station that has initially become connected with the trunk line may be dissociated .from such l line without rendering ineffective the locking out condition, and whereby such telephone rnay be restored to its connection with the trunk line so that during the' interval of disconnection of such telephone line .the trunk line may not be appropriated by another telephone station. p

` 5. A telephone system including two tele'- phone lines extending from telephone sta'- tions and each extending from' its own stationto the station of the other' line, there being rn'ean's goverened at the telephone stations whereby telephonie connection maybe effected between the stations; va third telephone line; means whereby either `of `said telephone stations may become connected with the third telephone lineaiidestablis'ha busy ytest condition in connection with the third telephone line, and whereby the telephone of the station initially becoming conhected with the third telephone line may be dissociated from said third line withoutrep moving said busy test condition and may be again restored to connection with said third line so that during the interval of disconne'ctibn of such telephone line the third tele" hone line niay not be appropriated by ano her station, and crnpl'emental 'apparatus at the stations of the, first aforesaid fuephone lines cooperating with the aforesaid means in 'performing the function for which it is premsa; y p

e; A telephone system iriduuingtw tlephone lines extending from telephone stationsy and each extending from its own station to the station of the thervline, there being meansl governed at the tele hone stations' whereby telephonie connection maf be effected between the stations athirt irelaphoh'e hhs; netas whereby hither o said with the third teleph ne lihe apparatus brought into',ooperativevreltibn with the third telephone ling thestation i"it`ally heihiag @ahahah therewith for' he; hg huttlephoic apparatus the't sttihs se@ ing the l haha telephone huh; means whereby t e telephbiie at the station that has ihitiany, @one eohh'te wif' the fhd thlephhhe the' lha" be (insediate from ehhh line withoiit l'i eing iiictiv the lf-:k out condition, and whereb telephone ihay berestored to itsconnectionA ith the third telephone line so' that t e interval of diseonnectin of tlphone line the third telephone line inay not be approprima by amatuer telephone hahha; and complerlhhthi hp'jh'fas at st'tih'ns' of the first aforesaid) telephone Hnesc `perating with the aforesaid means .in eizpniing the fuhh'tihh fof whihh itis ro eed. I

7. A hhiephhh Syst'rh'auiidihg two tlep lone' lines exten'ding from telephone stations and' efch extending from its own 'station tothe stationA of the ether line, there ilo being means governed at the telephone stations whereby telephonie connection may be effected between ti'e stations;A a te'lephone exchange; a trunk ine intervening between the Asttions of the aforesaid lines and said exchange; hahaha Whehhy either @if said tel,- e hone statins may become conr'iectedy with die' ahhh hhe had establish ahusy ts@ cohdition in cennectioii with the trunkJ `fine; fhahsjwhefehy the telephone' pf the s teioh ihiahuy becoming ohhh-haa with the trahi: line may be dissciatedfromsaid' tr'nk .line without remoying lSaid busy test coiiditin and may be again restored to connedton with said trunk line so that during in er val of disconneetionof telephone line the *flink ll H ly not aQPPsEdB- another station; anu compmehtal ap'p ratus at the stations of the first aforesaid telephone lines'coperating withthe aforesaid means in performing the function for which it is provided.

8. A telephone system including ytwo telephone lines extending from telephone st-ations and each extending from its own -station to the station of the other line, there being means governed at the telephone stations whereby telephonie connection may be effected between the stations; a telephone exchange; a trunk line intervening between the stations of the aforesaid lines and said exchange; means whereby either of said telephone stations may become connected with the trunk line; apparatus brought into cooperative relation with the trunk line by the station initially becoming connected therewith for locking out telephone apparatus of other stations seeking the trunk line; .and means whereby the telephone at the station that has initially become connected with the trunk line may be dissociated from such line without rendering ineffective the locking out condition, and whereby such telephone may be restored to its connection with the trunk line so that during the interval of disconnection of such telephone line the trunk line may not bevappropriated by another telephone station; and complemental apparatus at the stations of the first aforesaid telephone lines coperating with the aforesaid means in performing the function for which it is provided.

9. A telephone exchange system including a plurality of telephone lines extending from subscribers telephone stations to a telephone exchange; a plurality'of trunk lines intervening between said telephone exchange and the subscribers telephone stations of the aforesaid lines; means whereby either of said telephone stations may become connected with the trunk lines; signal apparatus at the telephone exchange adapted for association with the trunk lines; electro-magnetic means common to the trunk lines for governing said signal apparatus; andu means at the stations for interchangeably associating the latter means with said trunk lines.

10. A telephone exchange system including a plurality of telephone lines extending from subscribers a telephone exchange; a plurality of trunk lines intervening between said telephone exchange and the subscribers telephone stations of the aforesaid lines; means whereby either of said telephone stations may become connected with the trunk lines; signal apparatus at the telephone exchange adapted for association with the trunk lines; electromagnetic means interchangeably associated with said trunk lines operating in conjunction with said telephone stations for governing said' signal apparatus; and means for preventing other telephone stations from telephone stations to y effecting operative connection with a trunk line with which the aforesaid means has become operatively associated.

11. A telephone system including two telephone lines each extending from a subscribers station to a telephone exchange and from its own station to the station of the other line, there being means governed at the telephone stations wherebyV telephonie connection may be effected between the stations; a plurality of trunk lines intervening between said telephone exchange and the telephone stations of the aforesaid lines; means whereby either of said telephone stations may become -connected with the trunk lines; signal apparatus at the telephone exchange adapted for association with the trunk lines; means common to the trunk lines for governing said signal apparatus; and means at the stations for interchangeably associating the latter means with said trunk lines.'

12. :A telephone system including two telephone lines each extending from a subscribers station to a telephone exchange and from its own'station to the station of the other line, there being means -governed at the ltelephone stations whereby telephonic connection may be effected between the stations; a plurality of trunk lines intervening between said telephone exchange and the telephone stations of the aforesaid lines; means whereby either of said telephone stations may become connected with the trunk lines; signal apparatus at the telephone exchange adapted for association with the trunk lines; electro-magnetic means common to the trunk lines for governing said signal apparatus; and means at the stations for interchangeably associating the latter means with said trunk lines.

13. A telephone system including two telephone lines each extending from :i subscribers station to a telephone exchange Vand from its own station to the station of the other line, there being means governed at the telephone stations whereby telephonie connection may be effected between the stations; a plurality of trunk lines intervening between said telephone exchange and the telephone stations of the aforesaid lines; means whereby either o f said telephone stations may become connected with the trunk lines; signal apparatus at the telephone exchange adapted for association with the trunk lines; means common to the trunk lines for governing said signal apparatus; means at the stations for interchangeably associating the latter means with said trunk lines, and means forpreventing other telephone stations from effecting operative connection with a trunk line with which the aforesaid means has become operatively associated.

` 14:. A telephone system including two telephone lines each extending from a subother line, there being means governed at the telephone stations Whereby telephonie connection may be efected between the stations; a plurality of trunk lines intervening between said telephone exchange and the telephone stations of the aforesaid lines; means whereby either of said telephone sta# tions may become connected with the trunk lines; signal apparatus at the telephone eX- change adapted for association with the trunk lines; electro-magneticmeans interchange' ably associated with said trunk lines operating in conjunction with said telephone stations for governing said signal apparatus; and means for preventing other telephone stations from effecting operative connection with a trunk line With Which the aforesaid means has become operatively associated.

In -Witness whereof, I hereunto subscribe my name this twentythird day of March, A. D. 1911.

ELMER R. CORWIN.

Witnesses G, L. CRAGG, E. L. WHITE. 

